Pendulum type sensors of the general type disclosed herein are shown in the prior art United States patents to Porter et al U.S. Pat. No. 3,717,731 issued Feb. 20, 1973; Porter U.S. Pat. No. 3,717,732 issued Feb. 20, 1973; Brooks et al U.S. Pat. No. 3,678,763 issued July 23, 1972; and Orlando U.S. Pat. No. 3,710,051 issued Jan. 9, 1973. Generally such sensors include an acceleration responsive mass which is suspended by a deflectable wire within a sector shaped recess. Either a magnet or the deflection of the wire or both provides a preload bias on the mass normally locating the mass in unactuated position in engagement with the angular side walls of the recess adjacent the proximal ends thereof. Electrical contacts located adjacent the distal end of the recess are engaged by the mass to close an electrical circuit when the mass is subjected to a pulse of predetermined amplitude and time sufficient to overcome the preload bias and move the mass through the recess and into engagement with the contacts.